Davis Instruments Radiation Sensor Solar. (Already included with Vantage Pro Plus and Vantage Pro2 Plus.)Measures solar radiation and is required (along with an anemometer and a temperature/humidity sensor) if you wish to monitor evapotranspiration. Diffuser element and housing are carefully designed for accurate cosine response. Silicon photo diode provides good match to solar spectrum. Two-piece housing minimizes radiation heating allows convection cooling of the sensor and prevents the trapping of water or dust. Includes built-in level and 2' (0.6M) cable. Compatible with both original Vantage Pro and Vantage Pro2. You may also need a UV Sensor (#6490) and Sensor Mounting Shelf (#6673). Specifications for Davis Instruments Solar Radiation Sensor: Manufacturer: Davis Instruments Color: Black Package Contents: Davis Instruments Solar Radiation Sensor Davis Instruments 6450: Radiation Sensor Solar